Influence of temperature on phase, microstructure and oxidation resistance of carbon/carbon composites modified by hydrothermal treatment

Abstract

Carbon/carbon (C/C) composites were modified by a hydrothermal treatment using phosphoric acid solution, B4C, SiC and Al2O3 powders as infiltration fillers. The influence of the hydrothermal treatment temperature on the phase, microstructure and anti-oxidation property of the as modified composites was investigated. The phase composition and microstructure of the modified composites before and after oxidation were characterised by X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy techniques. Results show that the oxidation resistance of the C/C composites is effectively improved after modified by the hydrothermal treatment. The mass loss of the C/C composites modified at different hydrothermal temperatures increases parabolicly with increased oxidation time, while the relationship between hydrothermal temperature and mass loss of the modified C/C composites after oxidation at 700°C for 10 h reveals a linear dependence. The mass loss of the modified C/C composites is only 3·69×10−3 g cm−2, which is much lower than 141·55×10−3 g cm−2 of the non-modified C/C composites, after oxidised at 700°C in air for 10 h.